Wheel/Spoke Magnets

On Mon, 13 May 2019 20:52:15 +0200, Tosspot
wrote:
On 13/05/2019 02:37, sms wrote:
On 5/12/2019 4:26 PM, Mark J. wrote:
On 5/12/2019 6:27 AM, sms wrote:
On 5/12/2019 1:29 AM, Tosspot wrote:
Anyone know of some 'decent' ones. The Sigma supplied ones
won't attract a whore in a crack house. The Bosch type ones
always seem to corrode and fall off, and on top of that are
easy to X-Thread. The Cat-Eye ones don't seem to stay put[1].
The Echowell/Yamaha ones seem pretty decent but are like
rocking horse **** this side of the pond. Any other ideas?

[1] Yes, it is getting OCD!

When I lost the cadence magnet on my crank I used a hard-drive
magnet, i.e. https://www.ebay.com/itm/173209158372 but I got
some used ones from someone I knew at a disk drive company. I
heat shrinked it over the crank. I guess for a wheel magnet you
could use some cable ties or some baling wire and attach one of
these to the spokes. The pick-up doesn't have to be so close to
the magnet when you use a disk drive magnet.

If heat shrink is too much trouble, the ?vinyl? stretchy plastic
electrical tape works pretty well also, I've done this for cadence
magnets. The tape may start to peel and degenerate into a sticky
mess, but if caught/redone in time, the mess is quite
containable.

On 5/12/2019 6:27 AM, sms wrote:
On 5/12/2019 1:29 AM, Tosspot wrote:
Anyone know of some 'decent' ones. The Sigma supplied ones won't
attract a whore in a crack house. The Bosch type ones always seem to
corrode and fall off, and on top of that are easy to X-Thread. The
Cat-Eye ones don't seem to stay put[1]. The Echowell/Yamaha ones seem
pretty decent but are like rocking horse **** this side of the pond.
Any other ideas?

[1] Yes, it is getting OCD!

When I lost the cadence magnet on my crank I used a hard-drive magnet,
i.e. https://www.ebay.com/itm/173209158372 but I got some used ones
from someone I knew at a disk drive company. I heat shrinked it over the
crank. I guess for a wheel magnet you could use some cable ties or some
baling wire and attach one of these to the spokes. The pick-up doesn't
have to be so close to the magnet when you use a disk drive magnet.

If heat shrink is too much trouble, the ?vinyl? stretchy plastic
electrical tape works pretty well also, I've done this for cadence
magnets. The tape may start to peel and degenerate into a sticky mess,
but if caught/redone in time, the mess is quite containable.

Mark J.

I bonded used Hard disk magnets onto the aluminum crank arms of all of
my (4) bicycles as much as 10 years ago using epoxy glue. To date the
magnets are all still attached :-)

As to the original post, I have spoke magnets that I attached to front
wheels both with radial spokes and with crossed spokes that have been
in place for 4 - 5 years.

What is the big problems with attaching magnets to bicycles?

It isn't a problem per se. For some reason there is a *big* gap between
the spokes and the Surly LHT frame, which means at best, standard
magnets are intermittent. The fix is obvious, a small neodymium disc
magnet, but this tends to cause enough of some adverse force to cause
the above problems. In short, the Sigma ones don't cut the mustard,
different ones work ok for a year or two. I want a good magnet, that
stays put, doesn't corrode and I can't fyckup fitting.

I think that you are referring to a cycle meter pickup - spoke magnet
and sensor mounted on the front fork? What I do is mount the magnet
and than mount the sensor with a bit of offset - bent in, one might
say. Works for me :-)

The indomitable Sheldon recommends installing the magnet as near the
hub as possible as it means that the magnet passes the sensor
(transmitter) slower which he feels might make things more accurate.

As an aside, it also means that the magnet is closer to the fork tube
and therefore the sensor is closer to the magnet and requires less
offset. See https://www.youtube.com/watch?v=q-eGGDFeaUM
for an example (I know it is a cabled meter but the position of the
sender is the same as a wireless sensor).

--

Cheers,

John B.

Some wireless magnets NEED to be mounted close to the rim in order to be picked up by the sensor which also needs to be as close to the actual computer unit as possible. I had a wireless computer that had intermittent readings and readings far in excess of my actual speed. Those problems were corrected when the magnet and sensor were moved as far up the wheels and fork as possible. It seems that the distance that the sensor was from the computer was a critical factor with that computer as it was a very short range from the sensor to the unit that worked.

Cheers

Yes, I have had meters that required the sensor to be mounted as close
to the instrument as possible. Notably the cheap in price meters. I
have not found this to be true in the more "expensive" brands, such as
CatEye for example.

Although I've not found CatEye to be really "expensive" in the real
sense. I recently gave away a bike with a CatEye "cable" meter that
had been installed for 10 or more years and was still going strong. In
fact I can't remember even having changed the battery in that thing
:-)

--
Cateye has a spec for that. Magnet to sensor 5mm, sensor to
receiver 70cm for the current Urban Wireless. Just a few
years ago that was 2mm and 40cm which was difficult to set
up on some large bikes.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

On 5/12/2019 6:27 AM, sms wrote:
On 5/12/2019 1:29 AM, Tosspot wrote:
Anyone know of some 'decent' ones. The Sigma supplied ones won't
attract a whore in a crack house. The Bosch type ones always seem to
corrode and fall off, and on top of that are easy to X-Thread. The
Cat-Eye ones don't seem to stay put[1]. The Echowell/Yamaha ones seem
pretty decent but are like rocking horse **** this side of the pond.
Any other ideas?

[1] Yes, it is getting OCD!

When I lost the cadence magnet on my crank I used a hard-drive magnet,
i.e. https://www.ebay.com/itm/173209158372 but I got some used ones
from someone I knew at a disk drive company. I heat shrinked it over the
crank. I guess for a wheel magnet you could use some cable ties or some
baling wire and attach one of these to the spokes. The pick-up doesn't
have to be so close to the magnet when you use a disk drive magnet.

On 13/05/2019 16:56, Jeff Liebermann wrote:
On Sun, 12 May 2019 06:27:51 -0700, sms
wrote:
On 5/12/2019 1:29 AM, Tosspot wrote:
Anyone know of some 'decent' ones. The Sigma supplied ones won't
attract a whore in a crack house. The Bosch type ones always
seem to corrode and fall off, and on top of that are easy to
X-Thread. The Cat-Eye ones don't seem to stay put[1]. The
Echowell/Yamaha ones seem pretty decent but are like rocking
horse **** this side of the pond. Any other ideas?

[1] Yes, it is getting OCD!
When I lost the cadence magnet on my crank I used a hard-drive
magnet, i.e. https://www.ebay.com/itm/173209158372 but I got
some used ones from someone I knew at a disk drive company. I heat
shrinked it over the crank. I guess for a wheel magnet you could
use some cable ties or some baling wire and attach one of these to
the spokes. The pick-up doesn't have to be so close to the magnet
when you use a disk drive magnet.

I tried a disk drive magnet and had problems. The typical magnet is
not a single piece of iron with a single pair of poles, but rather
two magnets with two pairs of poles:
https://physics.stackexchange.com/questions/12283/if-you-place-a-spring-on-a-neodymium-hard-drive-magnet-it-appears-to-vibrate-in

By adjusting the position and orientation, it worked quite well.
However, if the magnet moved, I would get erratic operation. I got
my best resuls by breaking a magnet in half, resulting in (mostly)
one pair of poles. I don't recall which brand of bicycle computah I
used, but I think it may have been a Sigma.

Well, one old HDD reduced to component parts, we'll see how it goes over
the weekend.

On 5/12/2019 6:27 AM, sms wrote:
On 5/12/2019 1:29 AM, Tosspot wrote:
Anyone know of some 'decent' ones. The Sigma supplied ones won't
attract a whore in a crack house. The Bosch type ones always seem to
corrode and fall off, and on top of that are easy to X-Thread. The
Cat-Eye ones don't seem to stay put[1]. The Echowell/Yamaha ones seem
pretty decent but are like rocking horse **** this side of the pond.
Any other ideas?

[1] Yes, it is getting OCD!

When I lost the cadence magnet on my crank I used a hard-drive magnet,
i.e. https://www.ebay.com/itm/173209158372 but I got some used ones
from someone I knew at a disk drive company. I heat shrinked it over the
crank. I guess for a wheel magnet you could use some cable ties or some
baling wire and attach one of these to the spokes. The pick-up doesn't
have to be so close to the magnet when you use a disk drive magnet.

If heat shrink is too much trouble, the ?vinyl? stretchy plastic
electrical tape works pretty well also, I've done this for cadence
magnets. The tape may start to peel and degenerate into a sticky mess,
but if caught/redone in time, the mess is quite containable.

Mark J.

I bonded used Hard disk magnets onto the aluminum crank arms of all of
my (4) bicycles as much as 10 years ago using epoxy glue. To date the
magnets are all still attached :-)

As to the original post, I have spoke magnets that I attached to front
wheels both with radial spokes and with crossed spokes that have been
in place for 4 - 5 years.

What is the big problems with attaching magnets to bicycles?

It isn't a problem per se. For some reason there is a *big* gap between
the spokes and the Surly LHT frame, which means at best, standard
magnets are intermittent. The fix is obvious, a small neodymium disc
magnet, but this tends to cause enough of some adverse force to cause
the above problems. In short, the Sigma ones don't cut the mustard,
different ones work ok for a year or two. I want a good magnet, that
stays put, doesn't corrode and I can't fyckup fitting.

I think that you are referring to a cycle meter pickup - spoke magnet
and sensor mounted on the front fork? What I do is mount the magnet
and than mount the sensor with a bit of offset - bent in, one might
say. Works for me :-)

The indomitable Sheldon recommends installing the magnet as near the
hub as possible as it means that the magnet passes the sensor
(transmitter) slower which he feels might make things more accurate..

As an aside, it also means that the magnet is closer to the fork tube
and therefore the sensor is closer to the magnet and requires less
offset. See https://www.youtube.com/watch?v=q-eGGDFeaUM
for an example (I know it is a cabled meter but the position of the
sender is the same as a wireless sensor).

--

Cheers,

John B.

Some wireless magnets NEED to be mounted close to the rim in order to be picked up by the sensor which also needs to be as close to the actual computer unit as possible. I had a wireless computer that had intermittent readings and readings far in excess of my actual speed. Those problems were corrected when the magnet and sensor were moved as far up the wheels and fork as possible. It seems that the distance that the sensor was from the computer was a critical factor with that computer as it was a very short range from the sensor to the unit that worked.

Cheers

Yes, I have had meters that required the sensor to be mounted as close
to the instrument as possible. Notably the cheap in price meters. I
have not found this to be true in the more "expensive" brands, such as
CatEye for example.

Although I've not found CatEye to be really "expensive" in the real
sense. I recently gave away a bike with a CatEye "cable" meter that
had been installed for 10 or more years and was still going strong. In
fact I can't remember even having changed the battery in that thing
:-)

--
Cateye has a spec for that. Magnet to sensor 5mm, sensor to
receiver 70cm for the current Urban Wireless. Just a few
years ago that was 2mm and 40cm which was difficult to set
up on some large bikes.

--
Andrew Muzi
www.yellowjersey.org/
Open every day since 1 April, 1971

I'm too lazy to look up the spec now, but I had a bike computer/wris****ch/heart rate monitor that had a spec for all its senders (crank, fork, breast belt) to main unit of 18in max, and at that it didn't often work beyond 12in. In addition, even on my wrist it was out of spec. For north of STG300 I expected something more useful than a meter that forced me to crouch on my bike like a gorilla in too small a cage.

Andre Jute
Mind you, it was perfectly scaled to my bonobo (a sort of extra-intelligent chimpanzee), MiniAndre, who stood nearly 3ft high in his latex, or even sitting down on his unicycle.

I guess it's the new Fitbit by brother had. He had it die half way into the metric the other day. He said it was still charged but that it simply stopped working at 20 miles.